1. Field of the Invention
This invention relates to apparatus for periodic cultication of various microbodies of biological origin fed on solid, liquid or combination nutrient substrates, and more particularly to fermenters.
2. Description of Related Art
Any fermentation process involves a complex of interconnected biochemical, physicochemical and diffusive transformations dependent in their intensity mostly on the conditions of operation of the fermenter and its hydrodynamic characteristics.
For cultivating microorganisms, fungi, algae or separate tissues the microbiological practice has widely used flasks stopped by cotton filters and accommodating microbodies to be grown in a temperature-controlled rocker. Such devices are sufficiently simple and allow the growth of a range of various microbodies. However, despite their multipurpose application, their use is inherently confined in laboratory practice due to insufficient mass transfer. In addition, the flasks are not adaptable for cultivating microbodies of biological origin fed on solid nutritive substrates.
There are known different structural arrangements of fermenters; each such arrangement posessing hydrodynamic characteristics providing for the active growth of this or that type of microbody.
In particular, there is known a fermenter comprising a container with a stirring unit in the form of a multistage mixer (cf., e.g., E. U. Viestur, et al "Kultivirovanie mikroorganizmov"--Cultivation of Microorganisms, in Russian, Moscow, 1980, pp. 141 to 171).
This fermenter can be used for growing bacteria of yeast on a liquid nutritive medium and is not adapted for operation on solid or combination-type substrates.
The stirring units used in these fermenters tend to produce excessive foam in the cultural liquid, whereas for damping or supressing the foam use is made of mechanical, chemical or combined foam suppression, which affects the process parameters. In addition, the above apparatus provide only for cultivation of one or two types of microorganisms, such as yeast or bacteria.
There is also known a fermenter comprising a container provided with a heat-transfer jacket, a bacterial filter disposed in its inlet, an aerator, and a stirring unit in the form of a vertical circulation tube having a membrane accommodated under its lower end and connected with a drive (cf., a pamphlet of the Bioengineering AG Company, Switzerland).
The fermenter of its construction is adapted for use with bacteria or yeast fed on liquid nutritive substrates. The saturation of the cultural liquid with the oxygen of the air and mixing thereof in such a fermenter is assured by sucking in the air through the aerator to the vertical circulation tube accompanied by the formation therein of a gas-liquid mixture.
This fermenter is not capable of growing fungi, algae and separate tissue, and is not adapted for carrying out the processes of microbiological transformation of biologically active substances by using immobilized cells; it is also not adapted to operate on solid or combination substrates.
This is accounted for by the fact that aeration in said fermenter takes place by virtue of suction of air by a jet of liquid with the escape velocity thereof depending on its viscosity. Thus, during cultivation of mycelium the speed of flow of the cultural liquid is sharply reduced, and aeration terminates completely.
The free access of the substrate to the membrane prevents the fermentation process using solid or combination substrates, because such insoluble substrates (e.g., straw, wood saw dust, coal, etc.) tend to block the inlet of the circulation tube to result in plugging thereof and termination of the fermentation process.
For similar reasons the use of the above fermenter for carrying out processes involving a separate tissue or immobilized cells is impossible.